In 26 patients (mean age at death 68 plus/minus 9 years) who had undergone amputation (at mean age 63 plus/minus 12 years) of one or more lower extremities due to severe peripheral arterial atherosclerosis, the amounts of narrowing at necropsy in the major (left main, left anterior descending, left circumflex, and right) epicardial coronary arteries were determined. During life 15 (58%) of the 26 patients had symptoms of myocardial ischemia: angina pectoris alone in 1, acute myocardial infarction alone in 5, and angina and/or infarction plus congestive heart failure or sudden coronary death in 9. Twelve (42%) of the 26 patients died from consequences of myocardial ischemia: acute myocardial infarction in 5; sudden coronary death in 3; chronic congestive heart failure in 3, and shortly after coronary bypass surgery in 1. Grossly-visible left ventricular necrosis and/or fibrosis was present in 21 (81%) patients. Of the 26 patients, 24 (92%) had narrowing 76-100% in cross-sectional area of 1 or more major coronary arteries by atherosclerotic plaque. The mean number of coronary arteries per patient severely (greater than 75%) narrowed was 2.3 plus/minus 1.0/4.0. Of the 104 major coronary arteries in the 26 patients, 60 (58%) were narrowed greater than 75% in cross-sectional area by plaque. The 4 major coronary arteries in the 26 patients were divided into 5-mm segments and a histologic section, stained by the Movat method, was prepared from each segment. The mean percents of the resulting 1322 five-mm segments narrowed in cross-sectional area 0 to 25%, 26-50%, 51 to 75%, 76 to 95% and 96 to 100% were 17, 20, 35, 19 and 9%, respectively. The percents of 5-mm coronary segments narrowed greater than 75% in cross-sectional area were similar in each of the 4 major coronary arteries. Thus, patients with peripheral arterial atherosclerosis severe enough to warrant amputation nearly always have diffuse and severe coronary atherosclerosis at the time of necropsy.